nfssec(5)

NAME

nfssec– overview of NFS security modes

DESCRIPTION

The mount_nfs(1M) and share_nfs(1M) commands each provide a way to specify the security
mode to be used on an NFS file system through the sec=mode option. mode can be either sys, dh, krb5, krb5i, krb5p, or none. These security modes may also be added to the automount maps. Note that mount_nfs(1M) and automount(1M) do not support sec=none at this time.

The sec=mode option on the share_nfs(1M) command line establishes the security mode of NFS servers. If the NFS connection uses the NFS Version 3 protocol, the NFS clients must query the server for the appropriate mode to use. If the NFS connection uses the NFS Version 2 protocol, then the NFS client will use the default security mode, which is currently sys. NFS clients may force the use of a specific security
mode by specifying the sec=mode option on the command line. However, if the file system on the server is not shared with that security mode, the client may be denied access.

If the NFS client wants to authenticate the NFS server using a particular (stronger) security mode, the client will want to specify the security mode to be used, even if the connection uses the NFS
Version 3 protocol. This guarantees that an attacker masquerading as the server does not compromise the client.

The NFS security modes are described below. Of these, the krb5, krb5i, krb5p modes use the Kerberos V5 protocol for authenticating and protecting the shared filesystems. Before these can be used, the system
must be configured to be part of a Kerberos realm (see SEAM(5).

sys

Use AUTH_SYS authentication. The user's UNIX user-id and group-ids are passed in the clear on the network, unauthenticated by the NFS server. This is the simplest
security method and requires no additional administration. It is the default used by Solaris NFS Version 2 clients and Solaris NFS servers.

dh

Use a Diffie-Hellman public key system ( AUTH_DES, which is referred to as AUTH_DH in the forthcoming Internet RFC).

krb5

Use Kerberos V5 protocol to authenticate users before granting access to the shared filesystem.

krb5i

Use Kerberos V5 authentication with integrity checking (checksums) to verify that the data has not been tampered with.

krb5p

User Kerberos V5 authentication, integrity checksums, and privacy protection (encryption) on the shared filesystem. This provides the most secure filesystem sharing, as all traffic is encrypted. It should be noted that performance might
suffer on some systems when using krb5p, depending on the computational intensity of the encryption algorithm and the amount of data being transferred.

none

Use null authentication ( AUTH_NONE). NFS clients using AUTH_NONE have no identity and are mapped to the anonymous user nobody by NFS servers. A client using a security mode other than the one with which a Solaris NFS server shares the file system will have its security mode mapped to AUTH_NONE. In this
case, if the file system is shared with sec=none, users from the client will be mapped to the anonymous user. The NFS security mode none is supported by share_nfs(1M), but not by mount_nfs(1M) or automount(1M).